1. Field of Invention:
The present invention relates generally to machines adapted to deform material, and more particularly to a bending machine for bending a flat sheet of material into a cylinder or cone.
2. Status of Prior Art:
Bending machines are known in which the bending of the sheet results from passing the sheet between a support roll and an assembly of crenelated rolls with axes parallel to the axis of the support roll and generally located above it. The cylindrical surfaces of the crenelated rolls penetrate into each other and the radius of bend is defined by whether the support roll is closer to or further from the assembly of crenelated rolls.
The main problem posed by such bending machines is the flexing of the rolls and, more particularly, of the support roll which behaves in the manner of a beam that is necessarily rather long and thin. One solution to this problem is to impose a corresponding flexure on the opposing rolls, in the present case, the crenelated rolls. In order to effect this solution, but also for other reasons, there has also been proposed the use of a press roll of a diameter comparable to that of the support roll and of rollers which exert a differentiated pressure on the possibly inflected press roll, due to which the crenelated rolls merely transmit the pressure of the press roll, without their bearings being subjected to any substantial force.
This prior art is clearly described in the French publications FR-A No. 2 411 647 and FR-A No. 2 528 335, both in the name of the present applicant. The improved bending machine disclosed in the last-mentioned publication has given excellent results as to the precision of the radius of bend obtained. However, due to the biaxial displacement of the trains of crenelated rolls, this machine lends itself poorly to high-output work.